Because its a Free School and not accountable to the people and does not teach (to my knowledge anyway) the National Curriculum (which is far from perfect mind although you will know more about that than me) or have national pay scales. Its basically stealth privatisation.
Well, while I'm not fully supportive of the way Free Schools and Academies have been implemented in certain places, there are positives attached to them which the Unions are afraid to tell the truth about. The pay one is always an interesting one. We don't have Free Schools or Acadamies in Wales, bit there are a number over the border in Bristol and those areas. Some of the academies over there have been head hunting teachers from Wales with far more competitive salaries than the National Pay Scale allow. As someone who was Privately educated these Free schools-Academies are nothing like that and will increase funding through other ways